This invention relates to a process for the production of a fermented soya sauce.
A traditional oriental process for the production of a fermented soya sauce essentially comprises preparing koji in a first step, preparing and fermenting moromi in a second step and refining in a third step.
In this traditional process, cooked soya beans and/or a cooked, defatted soya flour are mixed with roasted wheat, the mixture is inoculated with a culture of koji or with a pure culture of spores of Aspergillus oryzae and/or Aspergillus sojae, cultured by aerobiosis and stirred intermittently for one to four days which gives the koji. The koji is mixed with a brine containing approximately 22 to 25% by weight sodium chloride which gives the moromi. The moromi is left to ferment for about 6 to 8 months and then refined by filtration and pasteurization.
A fermented soya sauce obtained by a traditional process such as described above has an .alpha.-amino nitrogen content approaching 50% of the total nitrogen.
A major disadvantage of this traditional process is its duration which is necessary for ensuring that the sauce acquires all its aroma through the slow and progressive action, during fermentation of the moromi, of the enzymes produced during preparation of the koji, microorganisms which produce lactic acid and are resistant to the high salt content (halophiles), particularly Pediococcus halophilus, and yeasts which produce aromatic substances and alcohol, particularly Saccharomyces rouxii.
Accordingly, various processes have been proposed for shortening this duration. U.S. Pat. No. 4,684,527, for example, describes a process which comprises preparing a koji, hydrolyzing the koji and contacting the hydrolyzate with an immobilized peptidase and glutaminase in the presence of salt.
Similarly, U.S. Pat. No. 4,587,127, for example, describes a process which comprises hydrolyzing a cooked mixture of defatted soya and wheat with a solution of enzymes extracted from a koji, contacting the hydrolyzate with immobilized cells of a halophilic lactic bacterium and then fermenting the whole for a few hours with a yeast of soya sauce.